In industry, polymeric resin films have a wide variety of applications including bases for packing, photographic films, condensers, electric insulators, labels, magnetic recording media, medical purposes. In recent years, polymeric resin films have also been in widespread use as base materials for picture display devices such as rear projection type screens, plasma display panels or liquid crystal display devices.
Since light diffusing film bases require high transparency, resin films prepared from transparent polymeric resin, such as polyester resin, polyacryl resin or polycarbonate resin, are mainly used in the light diffusing films.
Specifically, polyethylene terephthalate (PET) films are commonly used since they are cheap, highly transparent and sufficiently resistant to light and heat emitted from a backlighting unit, and have excellent mechanical strength and processibility.
However, since PET has organic or inorganic particles added to the inside or surface thereof for the purpose of increasing processibility and durability, the ability to control its transparency is unavoidably limited.